Arc length adjust function.

弧长调节功能。

I mean, arc length could be positive or negative.

我意思是弧长可正可负。

So, the usual notation that we will have is for arc length.

通常我们用符号s来表示弧长。

Well, so in particular, how do you relate arc length and time?

尤其是你怎么把弧长和时间联系起来？

So, the next concept that I want to define is that of arc length.

接下来我想介绍一下弧长。